ASHRAE 93-77 Instantaneous and All-Day Tests of the Sunpak™ Evacuated-Tube Collector

[+] Author and Article Information
G. R. Mather

Owens-Illinois, Inc., P. O. Box 1035, Toledo, Ohio 43666

J. Sol. Energy Eng 102(4), 294-304 (Nov 01, 1980) (11 pages) doi:10.1115/1.3266194 History: Received September 19, 1980; Online November 11, 2009


The results of ASHRAE 93-77 instantaneous and all day tests for two Sunpak™ evacuated-tube collectors are presented and discussed in terms of a simple dynamic response model and a biaxial incidence angle modifier approximation. The dynamic model predicts, and experimental results confirm, a residence time type of response rather than the exponential response that is assumed to characterize most collectors. The anisotropic geometries of the two collectors require that their optical properties be described by an incidence angle modifier that depends on both solar altitude and azimuth in the tilted aperture plane. The test results support the idea that this dependence can be characterized with sufficient accuracy by a biaxial approximation which requires that incidence angle modifiers be measured in each of two mutually perpendicular symmetry planes of the collectors. The all-day measurements are compared with the results to be expected from the ASHRAE 93-77 instantaneous tests, and excellent agreement is obtained when the dynamic model is used to account for the time variations in insolation and inlet temperature. It is concluded that the two Sunpak™ evacuated-tube models can be characterized adequately within the scope of ASHRAE 93-77, but that measurements over and above those actually required by this standard are necessary for a complete characterization. In addition, it is recommended that these collectors be tested on a tracking mount because of their long response times. Such instantaneous test results, in combination with the dynamic model, can be used to predict daily and long-term performance under most conditions.

Copyright © 1980 by ASME
Your Session has timed out. Please sign back in to continue.






Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In